Cops are threatened all the time. A threat has no credibility. They'll arrest you anyway, because they can, but they aren't afraid and they won't void your ticket or whatever it is that has you ranting. If you want to be taken seriously, you have to kill one then threaten to kill another. (Note that this might be illegal in your state. Check with a local lawyer before following my advice.)

mat catastrophe:Mrs. White: He threatened to kill me in public.Miss Scarlet: Why would he want to kill you in public?Wadsworth: I think she meant he threatened, in public, to kill her.Miss Scarlet: Oh.